This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Effects of Solver Parameters and Boundary Conditions on RANS CFD Flow Predictions over a Gen-6 NASCAR Racecar
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 29, 2022 by SAE International in United States
Annotation ability available
Racecar aerodynamic development demands rapid and incremental development cycles using extensive and well-correlated simulation data. The successful implementation of such a process is a major performance differentiator between race teams. Reynolds Averaged Navier-Stokes (RANS) simulations are an industry-wide tool of choice for their relatively quick turn-around times and cost-effectiveness. A limitation of RANS simulation is an inability to fully resolve flow separation and wake structures of the racecar geometry thereby reducing the accuracy of simulation and the confidence in incremental development work. However, race organizers of both Formula1 and NASCAR are placing increasing limits on aerodynamic development such as number of runs in a wind tunnel and CPU hours for CFD simulation. This prevents widespread use of LES or DES methodologies that require 5-10 times more computational resources. The confidence in a RANS simulation must increase to meet the development limitations while continuing to provide the necessary aerodynamic performance advantage. The current study aims to develop a framework that increases the confidence in RANS simulation using the popular SST k-ω turbulence model by evaluating the effects of solver parameters, closure coefficients and boundary conditions. For this a full-scale detailed model of a Gen-6 NASCAR was investigated using simulations run in the commercial CFD code Star-CCM+ (version 2020.2.1). The RANS simulations were validated against moving-ground, open-jet wind tunnel (Windshear) data using two ride-heights and two crosswind angles. The influence of realizability, compressibility, and simulation setup were analyzed. The proposed framework has shown good correlation in aerodynamic coefficients with lift and drag predictions within 2% of wind tunnel data thus providing high confidence in incremental aerodynamic development.
CitationMisar, A. and Uddin, M., "Effects of Solver Parameters and Boundary Conditions on RANS CFD Flow Predictions over a Gen-6 NASCAR Racecar," SAE Technical Paper 2022-01-0372, 2022, https://doi.org/10.4271/2022-01-0372.
- Grand , G. 2007 BMW Sauber F1 September 2007 https://www.topspeed.com/racing/f1/f1-cars/2007-bmw-sauber-f107-ar43720.html
- Duncan , B.D. and Golsch , K. Characterization of Separated Turbulent Flow Regions in CFD Results for a Pontiac NASCAR Race Car SAE Technical Paper 2004-01-3556 2004 https://doi.org/10.4271/2004-01-3556
- Singh , R. CFD Simulation of NASCAR Racing Car Aerodynamics SAE Technical Paper 2008-01-0659 2008 https://doi.org/10.4271/2008-01-0659
- Brzustowicz , J.P. , Lounsberry , T.H. , and de La Rode , J.M.E. 2002 Experimental & Computational Simulations Utilized During the Aerodynamic Development of the Dodge Intrepid R/T Race Car SAE Transactions 2387 2403
- Ashton , N. and Revell , A. Investigation into the Predictive Capability of Advanced Reynolds-Averaged Navier-Stokes Models for the DrivAer Automotive Model The International Vehicle Aerodynamics Conference 2014, November 125
- Ashton , N. , West , A. , Lardeau , S. , and Revell , A. Assessment of RANS and DES Methods for Realistic Automotive Models Computers & Fluids 128 2016 1 15
- Ashton , N. and Revell , A. Key Factors in the Use of DDES for the Flow Around a Simplified Car International Journal of Heat and Fluid Flow 54 2015 236 249
- Guilmineau , E. , Deng , G. , and Wackers , J. Numerical Simulation with a DES Approach for Automotive Flows Journal of Fluids and Structures 27 5-6 2011 807 816
- Uddin , M. , Mallapragada , S. , and Misar , A. Computational Investigations on the Aerodynamics of a Generic Car Model in Proximity to a Side-wall SAE Technical Paper 2018-01-0704 2018 https://doi.org/10.4271/2018-01-0704.
- Gan , E.C.J. , Fong , M. , and Ng , Y.L. CFD Analysis of Slipstreaming and Side Drafting Techniques Concerning Aerodynamic Drag in NASCAR Racing CFD Letters 12 7 2020 1 16
- Jacuzzi , E. , Barrier , A. , and Granlund , K.O. NASCAR Race Vehicle Wake Modification via Passive Blown Ducts and Its Effect on Trailing Vehicle Drag 2018 AIAA Aerospace Sciences Meeting 2018
- Jacuzzi , E. , Aleman Chona , M. , and Granlund , K.O. Improvements in NASCAR Race Vehicle Side Force and Yawing Moment Stability in Race Conditions Using Active or Passive Blowing AIAA Scitech 2019 Forum 2019 0592
- Fu , C. , Uddin , M. , and Robinson , A.C. Turbulence Modeling Effects on the CFD Predictions of Flow over a NASCAR Gen 6 Racecar Journal of Wind Engineering and Industrial Aerodynamics 176 2018 98 111
- Fu , C. , Uddin , M. , Robinson , C. , Guzman , A. et al. Turbulence Models and Model Closure Coefficients Sensitivity of NASCAR Racecar RANS CFD Aerodynamic Predictions SAE International Journal of Passenger Cars-Mechanical Systems 10 1 2017 330 345
- Fu , C. , Bounds , C.P. , Selent , C. , and Uddin , M. Turbulence Modeling Effects on the Aerodynamic Characterizations of a NASCAR Generation 6 Racecar Subject to Yaw and Pitch Changes Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233 14 2019 3600 3620
- Fu , C. , Uddin , M. , and Selent , C. The Effect of Inlet Turbulence Specifications on the RANS CFD Predictions of a Nascar GEN-6 Racecar SAE Technical Paper 2018-01-0736 2018 https://doi.org/10.4271/2018-01-0736
- Fu , C. , Bounds , C. , Uddin , M. , and Selent , C. Fine Tuning the SST k− ω Turbulence Model Closure Coefficients for Improved NASCAR Cup Racecar Aerodynamic Predictions SAE International Journal of Advances and Current Practices in Mobility 2019-01-0641 1 2019 1226 1232 https://doi.org/10.4271/2019-01-0641
- Fu , C. , Uddin , M. , and Zhang , C. Computational Analyses of the Effects of Wind Tunnel Ground Simulation and Blockage Ratio on the Aerodynamic Prediction of Flow Over a Passenger Vehicle Vehicles 2 2 2020 318 341
- Collin , C. , Indinger , T. , and Müller , J. Moving Ground Simulation for High Performance Race Cars in an Automotive Wind Tunnel-CFD Approach on Moving Belt Dimensions International Journal of Automotive Engineering 8 1 2017 15 21
- Soares , R.F. , Garry , K.F. , and Holt , J. 2017
- Elkhoury , M. Assessment of Turbulence Models for the Simulation of Turbulent Flows Past Bluff Bodies Journal of Wind Engineering and Industrial Aerodynamics 154 2016 10 20
- El-Behery , S.M. and Hamed , M.H. A Comparative Study of Turbulence Models Performance for Separating Flow in a Planar Asymmetric Diffuser Computers & Fluids 44 1 2011 248 257
- Gorji , S. , Seddighi , M. , Ariyaratne , C. , Vardy , A.E. et al. A Comparative Study of Turbulence Models in a Transient Channel Flow Computers & Fluids 89 2014 111 123
- Curley , A. , Uddin , M. , and Peters , B. Direct Numerical Simulation of Turbulent Flow around a Surface Mounted Cube 22nd AIAA Computational Fluid Dynamics Conference 2015 3431
- Chen , C.J. Fundamentals of Turbulence Modelling CRC Press 1997
- Pope , S.B. A Perspective on Turbulence Modeling Modeling Complex Turbulent Flows Dordrecht Springer 1999 53 67
- Argyropoulos , C.D. and Markatos , N.C. Recent Advances on the Numerical Modelling of Turbulent Flows Applied Mathematical Modelling 39 2 2015 693 732
- Wilcox , D.C. Reassessment of the Scale-Determining Equation for Advanced Turbulence Models AIAA Journal 26 11 1988 1299 1310
- Wilcox , D.C. 2006 Turbulence Modeling for CFD La Canada, CA ,
- Ahmed , S.R. , Ramm , G. , and Faltin , G. Some Salient Features of the Time-Averaged Ground Vehicle Wake SAE Transactions 1984 473 503
- Heft , A.I. , Indinger , T. , and Adams , N.A. Experimental and Numerical Investigation of the DrivAer Model Fluids Engineering Division Summer Meeting 44755 American Society of Mechanical Engineers 2012, July 41 51
- Menter , F.R. Improved Two-Equation k-Omega Turbulence Models for Aerodynamic Flows Nasa Sti/recon Technical Report N 1992
- Menter , F. Zonal Two Equation kw Turbulence Models for Aerodynamic Flows 23rd Fluid Dynamics, Plasmadynamics, and Lasers Conference 1993, July 2906
- Menter , F.R. Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications AIAA Journal 32 8 1994 1598 1605
- Menter , F.R. , Kuntz , M. , and Langtry , R. Ten Years of Industrial Experience with the SST Turbulence Model Turbulence, Heat and Mass Transfer 4 1 2003 625 632
- Heschl , C. , Inthavong , K. , Sanz , W. , and Tu , J. Evaluation and Improvements of RANS Turbulence Models for Linear Diffuser Flows Computers & Fluids 71 2013 272 282
- Howell , J. Aerodynamic Drag of Passenger Cars at Yaw SAE International Journal of Passenger Cars-Mechanical Systems 2015-01-1559 8 2015 306 316 https://doi.org/10.4271/2015-01-1559
- Bello-Millán , F.J. , Mäkelä , T. , Parras , L. , Del Pino , C. et al. Experimental Study on Ahmed’s Body Drag Coefficient for Different Yaw Angles Journal of Wind Engineering and Industrial Aerodynamics 157 2016 140 144
- Keogh , J. , Barber , T. , Diasinos , S. , and Doig , G. The Aerodynamic Effects on a Cornering Ahmed Body Journal of Wind Engineering and Industrial Aerodynamics 154 2016 34 46
- Guilmineau , E. and Chometon , F. Effect of Side Wind on a Simplified Car Model: Experimental and Numerical Analysis Journal of Fluids Engineering 131 2 2009
- Guilmineau , E. , Chikhaoui , O. , Deng , G. , and Visonneau , M. Cross Wind Effects on a Simplified Car Model by a DES Approach Computers & Fluids 78 2013 29 40
- Altinisik , A. , Yemenici , O. , and Umur , H. Aerodynamic Analysis of a Passenger Car at Yaw Angle and Two-Vehicle Platoon Journal of Fluids Engineering 137 12 2015
- Gogel , D. and Sakurai , H. The Effects of End Plates on Downforce in Yaw SAE Technical Paper 2006-01-3647 2006 https://doi.org/10.4271/2006-01-3647.
- Zhang , Y. , Yang , C. , Wang , Q. , Zhan , D. et al. Aerodynamics of Open Wheel Racing Car in Pitching Position SAE Technical Paper 2018-01-0729 2018 https://doi.org/10.4271/2018-01-0729.
- Dominy , R.G. and Le Good , G. The Use of a Bluff Body Wake Generator for Wind Tunnel Studies of NASCAR Drafting Aerodynamics SAE International Journal of Passenger Cars-Mechanical Systems 2008 1404 1410
- Walter , J. , Bordner , J. , Nelson , B. , and Boram , A. The Windshear Rolling Road Wind Tunnel SAE International Journal of Passenger Cars-Mechanical Systems 2012-01-0300 5 2012 265 288 https://doi.org/10.4271/2012-01-0300.
- Misar , A.S. , Uddin , M. , Robinson , A. , and Fu , C. Numerical Analysis of Flow around an Isolated Rotating Wheel Using a Sliding Mesh Technique SAE Technical Paper 2020-01-0675 2020 https://doi.org/10.4271/2020-01-0675.
- Misar , A.S. , Bounds , C. , Ahani , H. , Zafar , M.U. et al. On the Effects of Parallelization on the Flow Prediction around a Fastback DrivAer Model at Different Attitudes SAE Technical Paper 2021-01-0965 2021 https://doi.org/10.4271/2021-01-0965.